Bit and holding means therefor



Oct. 8, 1940. w c. L. BOWMAN I V (bar/es A Bowman BY ATTORNEY 5 Oct. 1940. I Q BOWMAN 2,217,348

BIT AND HOLDING MEANS THEREFOR Filed March 19, 1940 2 Shets-Sheet 2 INVENT OR.

BY I

\ H ATTORNEY.

Patented Oct. 8, 1940 UNITED STATES PA'iE'i' OFFICE Charles L. Bowman, Canton, Ohio, assignor to The Bowdil Company Application March 19,

15 Claims.

My invention relates in general to cutting bits and holding means therefor and more particularly to bits for cutting coal or other substances.

In the mining of coal or other substances, it is highly desirable in the interest of economy and the saving of power that the cutting bits of a cutter chain be not only strong and durable but also eificient in operation.

My cutting bit and holding means constitute improvements upon the disclosure of United tates Patent No. 1,677,950 issued to Newton K. Bowman on July 24, 1928. In order to provide additional backing for the cutting point of the bit, the acute angle of the rhomboid at the cutting point may be made larger. The increase of this angle, however, foreshortens the bit unless the body of the bit is made correspondingly longer. It is also desirable for reasons of efficiency to use a relatively long bit extending a considerable distance outwardly from the holding means to provide a good cutting action free from interference of the holding means. At the same time, it is very desirable that the maximum thickness of the bit be limited as otherwise requiring an excessively large and wide holding means limiting the efficiency of the combined unit. My present invention makes possible the obviating of the limitations of the prior bits and affords a structure having distinctly advantageous features to be observed in the description and drawings of the embodiment thereof.

An object of my invention is the provision of a cutting bit which requires a minimum amount of power to operate and which will withstand a considerable amount of hard usage.

Another object of my invention is the provision of a cutting bit which produces very little drag and which has a relatively large amount of backing to prevent the rapid wearing away of the points of the bit .as well as to eliminate breakage. 40 Another object of my invention is to increase the backing of the cutting points of a rhomboidal bit by making the angle of the rhomboid at the cutting points larger and by providing a 45 central body portion to increase the length of the bit.

Another object of my invention is to make my bits have relatively narrow cutting faces with a relatively large amount of backing to give strength to the cutting faces.

Another object of my invention is the provision of a rhomboidal bit in side elevation having substantial double diamond shaped offset faces.

Another object of my invention is the provision of holding my bits in a chain lug.

1940, Serial No. 324,840

Another object of my invention is the provision of a cutting bit having a depressed portion intermediate its ends for receiving a portion of holding means for the bit.

Another object of my invention is the provision of a cutting bit having a reduced thickness located centrally of its ends to accommodate complementary portions of the bit holding means.

Another object of my invention is the provision of a cutting bit having a cutting point at an upper end thereof and having a shoulder extending laterally of the bit at a location intermediate the lower end and the central portion thereof, the said shoulder being adapted to engage holding means.

Another object of my invention is the provision for securely holding the lower half of a cutting bit to permit a maximum amount of the length of the bit to extend upwardly therefrom.

Another object of my invention is the provision of an improved arrangement of a cutting bit and holding means.

Another object of my invention is the provision of an improved holding means for a cutting bit.

Another object of my invention is the provision of a double ended cutting bit having spaced shoulders adjacent opposite ends for facilitating the holding of said bit by holding means.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational view of a cutter chain lug, partly in section, showing my new improved bit and holding means therefor;

Figure 2 shows a side elevational View of my cutting bit; I

Figure 3 shows a front elevational View of my cutting bit;

Figure 4 shows a view similar to Figure 1, except that the means for holding the bit in the chain lug is of a modified character;

Figure 5 is a view of the holder adapted to engage the cutting bit;

may be made of hard steel in order to withstand the severe cutting operation to which it is sub jected. In side elevation, the bit is substantially rhomboidal and in front elevation its cutting faces l8 and 19 are substantially double diamond shaped.

As shown in Figure 1, my bit is adapted to be removably held in a holder ll seating in a lug recess i l of a cutter chain lug ll. A set screw l3 engaging the lowermost portion of the front face of the cutting bit securely holds the holder l l and the bit inthe lug recess i l. The rear face of the bit engages the front face 3d of the holder, which is provided with lateral sidewalls 35 for engaging the sides of the bit. The lowermost left-hand portion of the holder ii is provided with a projection l which looks under a come plementary recess of the lug and prevents the holder and the bit from lifting out of the lug recess i l of the chain lug l'l when the set screw [3 is turnedin tightly. The bottom of the lug recess M is provided with lateral side openings 55 to permit dust, dirt and other substances to escape,.keeping the lug recess it clean. The bottom of the holder ii is also provided with an opening !2 to permit dust, dirt and other substances to escape therefrom and allow the bit to set properly in the holder. The drawings &C-. companying the application are made substantially in accordance with the actual size of the bit and holding means.

With reference to Figure 3, the cutting faces are substantially double diamond shape and the central portion comprises two spaced relatively wide regions 2t and 2! with a reduced section therebetween having concaved side walls 2% and 30. The cutting points are designated by the reference characters 2% and El and the correspond ing edges of the bit by the reference characters 3i and 32. The side walls 22 and 23 of the bit between the relatively wide region 29 and the edge 35 of the bit are concave and produce a greater cutting clearance as the cutting point 26 wears away. The side walls 2% and 25 of the bit between the relatively wide region 2! and the edge 32 of the bit are concave and likewise produce a greater cutting clearance as the cutting point Zl wears away.

The smaller angle of the rhomboid at the cutting point 26 and El is relatively large to give an increased backing? to the cutting points so as to give longer life as well as to eliminate breakage of the points. The term backing means the thickness to the point of the bit taken in the direction of the travel of the bit when cutting. The angle is such that the cutting faces are ofi'set with respect to each other for substantially onequarter of the length of the cutting faces. That is tosay, the distance between the construction line 28 and the cutting point 26 which shows the ofiset relation of the two cutting faces represents substantially one-quarter of the length of the entire cutting face. The increasing of the smaller angle of the rhomboid at the cutting points of the bit considerably foreshortens the bit more 1 I than is desirable. It is preferable to have a sufficient length of cutting bit extending outwardly from the chain lug beyond the holding means toprovide the best cutting action. To provide a bit having the desired characteristics, I increase the length of the bit by adding the central body portion which elongates the bit by a distance substantially equal to the length of the arcuate or concave side walls 29 and 30. The length of the bitis such that when it isv setting in the holder I l, the exposed cutting point is substantially one and three-quarters inches above the forward top surface of the chain lug. This enables the lugs of the chain to pass around the round end of the cutter bar without striking the uncut coal. The side walls 29 and 30 are depressed or concaved so that they provide engageable holding surfaces which fit complementarily into the uppermost lateral side portions 3'5 of the lateral side or projecting walls 35. As shown in Figure 1, keeping in mind that the bit is reversible, the concave sides 24 and 25 between the relatively wide region 2! and the edge 32 complementarily fit within the lowermost portion 3i of the lateral side or projecting walls 35 of the holder.

The side portions 36 of the side walls 35 converge and engage the lateral converging sides of shoulders formed by the wide region 2! and lock the bit in position against longitudinal withdrawall. As the lateral shoulders formed by the wide region 2| are below the center line of the bit the arrangement permits the locking of the bit to be done on its lower half. The provision for locking the lower half of the bit allows for the extension of an increased length of bit from the holding means beyond that permitted by the prior looking arrangements, as for example that shown in said Bowman Patent No. 1,677,950.

In the described manner of assembly the rhomboidal bit can only be removed from the holder at a rhomboidal angle, because the uppermost portions 36 and the lowermost portions 31 of the side Walls 35 of the holder engage the side Walls of the bit which converge in opposite directions. The upper end 38 of the holder ll extends upwardly a short distance along the rear face 59 of the bit to give additional support to the cutting bit. In removing the bit from the holder l l, or reversing :it end-to-end, or when inserting a new bit, it is only necessary to unscrew the set screw it sufiiciently until the bit clears the side wall 35 and then the bitmay be removed from the lug recess M of the chain lug ll.

In Figure 4 I show a modified arrangement for holding the bit in the lug recess id, in that I employ in addition to the' holder ii a wedge a l which engages the front cutting face of the bit with lateral side walls ll engaging the converging walls 2d and 25between the central portion 2i and the edge 32. In this modified method of holding the bit, the wedge id is urged against the bit by means of a set screw it. In many applications it is desirable to eliminate the use of a wedge and abut the set screw directly against the face of the bit as shown in Figure l. The elongated face of my bit permits this to be done whereas a shorter face might not present a surface against which the set screw can abut and still make the cutting point of the bit substantially one and three-quarter inches, or therabout, above the top surface of the cutting chain lug.

In Figure 5 the holder H is shown alone and being a front View illustrates the disposition of the side or projecting wall portions 35 and 37 converging in the opposite directions and making complementary engaging portions for holding the bit.

Figure 6 being a cross-sectional view through the assembled Iparts shown in Figure 1, illustrates the disposition of the parts relative to each other. The interlocking of the side wall or projecting portions 36 and 31' with the concave walls of the bit is seen in this view. The'projecting portions 36 overhangande'ngage the converging sidesor shoulder portionszt and'afill of the bit formed'by the wide portion 2! andthus lock the lower half of the bit against longitudinal withdrawal. The projecting portions 3! underhang and engage the converging sides or shoulder portions 24 and 25 of the bit and prevent downward movement of the bit. The provision for holding the lower portion of the bit by this interlocking arrangement permits the extension of a greater portion of the length of the bit outwardly from the holding means to obtain an improved cutting action.

In Figures 7 and 8, there is shown a modified form of bit in which the rhomboidal walls have portions or sections angularly disposed relative to each other. The angular sides 56 extend toward the upper edge of the bit and the angular sides %9 extend toward the lower edge of the bit. Intermediate the wide regions 50 and 5! there is a concave or V-shaped recess having the angular sides ll and t8 meeting at the center line of the bit. The cutting points 52 and 53 are formed at the small angles of the rhomboid. In this modified form the interlocking of the lower portion of the bit with a holder is similar to that described for the preferred form of bit. The projecting walls or portions of a holder overhang and engage the converging sides or shoulders formed by the lower wide region of the bit to permit a maximum length of cutting bit to extend outwardly from the holding means. In the case of the angularly formed bit shown in Figures 7 and 8, the inner surfaces of the holder are modified to complement the angularly disposed walls of the bit.

Although I have described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. A double-ended bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces, said cutting faces being off-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions, the rhomboidal side Walls between the spaced regions being concaved to provide engageable holding surfaces and the side walls between the central body portion and the edge portions being concaved and producing a greater cutting clearance as the cutting points wear away.

2. A double-ended bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces, said cutting faces being off-set relative to each other for substantially one-fourth their length and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions, the rhomboidal side walls between the spaced regions being concaved to provide engageable holding surfaces and the side walls between the central body portion and the edge portions being concaved and producing a greater cutting clearance as the cutting points wear away.

3. A double-ended bit comprising a solid piece of metal having rhomboidal side walls and sub stantially parallel opposite end cutting faces, said cutting faces being off-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions with a reduced section therebetween to provide engageable holding surfaces, the side walls between the central body portion and the edge portions being concaved and producing a greater cutting clearance as the cutting points wear away.

4. A solid bit formed from a bar of stock which is substantially double diamond shape in crosssection having a substantially double diamond shaped cutting face disposed at an angle different than degrees to the longitudinal axis of the bar, the side faces of the bit having in-- termediate concave surfaces to provide engageable holding surfaces and end concave surfaces so as to provide a cutting clearance as the bit wears away.

5. A double ended solid bit formed from a bar of stock which is substantially double diamond shape in cross-section having substantially double diamond shaped parallel cutting faces disposed at an angle different than 90 degreesto the longitudinal axis of the bar, the side faces of the bit having intermediate concave surfaces to provide engageable holding surfaces and end concave surfaces so as to provide cutting clearances as the bitwears away.

6. A double-ended bit comprising a solid piece of metal having rhomboidal side walls and sub stantially parallel opposite end cutting faces, said cutting faces being off-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions with a reduced section therebetween to provide engageable holding surfaces, the side walls between the central body portion and the edge portions converging as the walls approach the edge portions.

7. The combination of a double-ended bit and 4 a holder, said bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces, said cutting faces being off-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions with a re.- duced'section therebetween to provide engageable holding surfaces, the side walls between the central body portion and the edge portions converging as the walls approach the edge portions, said holder having a front face portion engaging a cutting face of the bit and having lateral side portions engaging the holding surfaces of the reduced section of the bit.

8; The combination of a double-ended bit and a holder, said bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces, said cutting faces being ofi-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomboid, said bit having relatively narrow edge portions and a central body portion, said central body portion having two spaced relatively wide regions with a reduced section therebetween to provide engageable holding surfaces, the side walls between the centralbody portion and the edge portions converging .as the walls approach the edge portions, said holder having a front face portion engaging a cutting face of the bit and having lateral side portions engaging the holding surfaces of the retions and a central body portion, said central body portion having two spaced relatively wide regions with a reduced section therebetween to provide engageable holding surfaces, the side walls between the central body portion and the edge portions converging as the walls approach the edge portions, said holder having a front face portion engaging a cutting face of the bit and having lateral side portions engaging the holding surfaces of the reduced section of the bit, the lateral side portions of the holder also enaging the converging walls between the central body portion and one of the edge portions of the bit, said wedge engaging the bit on the opposite side from the holder and having lateral side portions engaging the said converging walls between the central body portion and said one of the end portions of the bit. 1

10. A cutting bit comprising a solid piece of metal having rhomboidal side walls and substantially parallel opposite end cutting faces, the bit having relatively narrow edge portions extending between the respective ends of said cutting faces, said rho-mboidal side walls having a laterally extending shoulder portion disposed at a distance from, and intermediate of, said narrow edge portions, the said shoulder portion being positioned at a greater distance from one edge portion than the other edge portion to interfit and lock with complementary holding means at said greater distance from said one edge portion.

11. A double-ended cutting bit comprising a solid piece of cutting material having rhombo-idal side walls and substantiall parallel cutting faces and substantially parallel narrow edge portions extending between the ends of said cutting faces, said bit being relatively wide between said side walls at local regions disposed intermediate said cutting faces, said cutting faces being off-set relative to each other and forming cutting points at the diametrically opposed sharper angles of the rhomlzoid, said bit having relatively narrow,

edge portions and a central body portion, said central body portion having two spaced relatively wide regions and a relatively narrow region intermediate of the wide regions to accommodate locking means adapted to inter-fit therewith.

13. A holder for a reversible cutting bit comprising a member having a back wall portion adapted to engage a. flat face of said cutting bit and to brace the bit in cutting action, the holder having two spaced side portions extending from said back wall to accommodate the bit therebetween, said two spaced side portions extending inwardly to fit into recesses formed in the sides of, and intermediate the ends of, said bit, the said side portions locking said bit against longitudinal withdrawal from said holder.

14. A holder for a cutting bit having a flat face and rhomboidal side walls, the bit having shoulder portions extending from said side walls intermediate its ends at a greater distance from the extending end than from the end held by said holder, the said holder having a backing portion adapted to engage said flat face and to support the bit in its cutting movement and having side portions adapted to extend along the side Walls of the bit and to overhang and engage said shoulder portions, the engagement of said side portions of the holder and said shoulder portions of the bit locking the lower portion of the bit against longitudinalwithdrawal of the bit from said holder.

15,. A solid bit formed, from a bar of stock having side walls defining relatively narrow edge portions and a central body portion and having a cutting face disposed at an angle difierent than 90 degrees to the longitudinal axis of the bar, said central body portion having two spaced relatively wide regions with a reduced section therebetween to provide engageable holding surfaces, the side walls between the central body portion and the edge, portions being concaved so as to provide a cutting clearance as the bit wears away.

CHARLES L. BOWMAN. 

